Wednesday, March 11, 2015

Protecting prairie remnants with adjacent planted prairies

This interesting research was carried out at Nature
Conservancy natural areas in four States: Loess Hills (Iowa); Glacial Ridge
(Minnesota); Nachusa Grasslands (Illinois); and Kankakee Sands (Indiana). In
all of these sites, prairie remnants existed embedded within extensive cropland
that had been partly planted to prairie. Thus, remnant--restoration pairs
existed, permitting a quantitative measure of impact of the planted prairie on
the adjacent native prairie. The hypothesis was that resistance to invasion and the richness
of the native flora would be greatest next to prairie restorations (planted prairies). Adjacent cropland, and roadsides would be progressively less
effective or ineffective in protecting adjacent remnants.

The experimental design involved laying transects from the
edges of the prairies to the center, and sampling at defined intervals.

It was found that nonnative
dominance was higher at the edges than in the interiors of prairies adjacent to
crops and to roadsides, whereas in prairies adjacent to restorations there was no edge effect on nonnative
cover (see Figure).

Nonnative dominance from the edge to the center of prairieremnants for different types of adjacent vegetation.

The implications of this study are clear. Prairie remnants
standing alone or adjacent to roadsides or crop fields have much greater chance
for invasion by nonnative species. Adjacent restorations can protect remnants
against invasion.

Many prairie remnants are adjacent to ag fields which are
suitable for planting to prairie. Since planting prairies is a relatively
inexpensive activity, these data provide strong encouragement to carry out such
plantings.

A further point: when prairie remnants are being acquired as
part of land acquisition programs, high priority should be given to sites with
extensive adjacent cropland or old fields suitable for prairie planting.